Conversion unit for gun type oil burners



April 5, 1949.. J. A. LOGAN 2,466,249

CONVERSION UNIT FOR GUN TYPE OIL BURNERS 2 Sheets-Sheet 1 Filed March 3, 1947 INV-ENTOR Jane /A. Loy/m 7 BY M ATTOR EYS April 5, 1949. J./ LOGAN 2,466,249 4 CONVERSION UNIT FGR GUN TYPE OIL BURNERS Filed March 3, .1947 2 Sheets-Sheet 2 IINVENTOR Joan/r 4.40m

Pat'ented Apr. 5, 1949 D TE PATENT, OFFICE"? couvnasronum'rr'oa GUN me on.

' i BURNEBS Joseph Logan, Hadley, 'Mass" assignor to Gilbert &'Ba'rker Manufacturing Company, West I I Spg'ngiield, Masa a corporation of Massachugg meals..- March 3, 1947, Serial no. 731,920

l 2 Claims.

This invention relates. to a conversion unit which, is adapted to be applied to a gun type, house heating oil burner and, when so applied,

enables the -burner to be. operated with greater efliciency during normal running intervals of operation, when the air fan and oil pump are moving at full speed, and without smoke and soot during-the; starting and stopping intervals of operation, when the fan and pump are respec-' tively accelerating or decelerating.

Ingthe ordinary gun type oil burner, the air and-'oil'for combustion are respectively supplied by afanandlpump driven by an electric" motor and moving synchronously with the motor at all times; ,The fan-is non-positive in action while the oil pump is positive in action. With such an arrangement, when the burner is started up a spray of atomized oil will be emitted from the .and a smoky flame occurs with resultingsoot deposits in the heater. Each starting interval and each stopping interval is short and of but a few seconds duration. However, the burner is started and stopped many times during each day and a small amount. of smoke during each such interval adds up to a lot of smoke during the heating season and a progressive accumulation of soot on the heat transfer surfaces of the heating apparatus.

One way of avoiding the diificulties described is to open the air control of the burner to admit more air and provide a. mixture which is so lean that it will not smoke. But this plan, although widely practiced heretofore, results in low efflciency of combustion during the normal running intervals of operation of the burner. The lean mixture, needed to stop the smoke nuisance during the short starting and stopping intervals, is continued during the relatively long normal running intervals of operation of the burner with a substantial loss in efllciency. Theoretically, the rate of air supply should be just enough to consume all the oil at the rate at which it is supplied. Practically, it is desirable to have the burner operate a closelyas possible to the theoretically correct air-oil ratio. This, however, cannot be done without getting smoky combustion The invention has for an object to provide an attachment for an oil, burner, comprising, an auxiliary fan which is adapted to be positioned in an additional air inlet provided for the burner fan and which is adapted to be driven by the burner fan by means of a centrifugal clutch only after the burner fan has attained a predetermined I speed, the auxiliary fan when stationary afl'ording by the spaces between its blades additional air inlets through which additional air may be drawn by the burner fan, the auxiliary fan when rotating opposing the action of themain burner fan and reducing the rate of air flow through said additional air inlet.

The invention also has foran object to provide driving means for the auxiliary fan including a coupling for driving engagement with the burner fan and a speed-responsive clutch, the driven element of which is connected to the auxiliary fan and has a connection for driving the oil pump.

The invention has for a further object to pro I vide with an oil burner attachment of the type described, a sleeve in which the auxiliary fan is adapted to be located, such sleeve adapted to surround an air inlet opening in the air shutter of the burner.

The invention will be disclosed with reference to the accompanying drawings, in which:

Fig. 1 is an exterior elevational view of an auxiliary fan and driving means therefor embodying the invention;

of 2-2 of Fig. 1;

Fig. 3 is a sectional elevational view taken on the line 33 of Fig. 2;

Figs. 4 and 5 are end and sectional elevational views, respectively, of a sleeve provided for the auxiliary fan and of a form which is adapted for attachment to the air shutter of a burner;

Figs. 6 and 7 are end and sectional eievational views of a sleeve provided for the auxiliary fan and of a form'which isintegral with a new air shutter that is adapted to be substituted for the Fig. 9 is a cross sectional view taken through the hub of the fan of the burner showing the manner of coupling thereto the driving means for the auxiliary fan.

Referring to these drawings; the conversion unit shown in Figssl, 2 and 3, includes an aux:- iliary fan I, adapted to be driven by the air supply fan of the burner, and a speed-responsive clutch for controlling the rotation of the fan, and preferably also the oil pump of the burner, as will later appear. This clutch includes a driving member 2, a driven member 3 in the shape of a drum, and suitable means carried by member 2 and adapted to be actuated by centrifugal force for the purpose of engaging and driving the member 3. The fan is as shown formed by blades projecting from the outer periphery of drum 3 and formed integrally with the drum during the operation of casting the same.

Conveniently, the driving member 2 has a ferrule 4 formed thereon, to which is suitably fixed one end of a short length of rubber hose 5, the other end of which is suitably fixed to another ferrule 6. The latter has its free end open, forming a socket I, adapted to fit over the hub of the fan of the burner. The cylindrical wall of the socket l is pressed inwardly to form a plurality (four as shown in Fig. 9) of splines 8, adapted to engage grooves in the hub of the burner fan for an operable driving engagement. The ferrule 6 has fixed thereon a collar 9 and threaded into the collar is a set screw l0, adapted to be 'turned inwardly to clamp the ferrule to the hub of the fan and hold it against axial movement.-

The arrangement affords a convenient means for coupling the driving member 2 to the fan of the burner. The rubber tube affords a flexible coupling, enabling the member 2 to be driven by the burner fan even if its axis is not exactly aligned with that of the burner fan.

The driven member 3 has coaxially-disposed outer and inner hubs II and [2 (Fig. 3) bored to receive an end of the drive shaft of the oil pump of the burner. The hub I has a set screw l3 threaded therein and adapted to, engage a flat on the oil pump shaft for an operable driving engagement. Pressed into a counterbore in the inner end of the inner huh I! is a bushing I4, affording a bearing toreceive one end of a stub shaft l5, the other end of which shaft is fixed in the driving member 2 and located coaxially thereof. The shaft l and the bushing |4 affords a means for holding the driving and driven members 2 and 3 of the coupling in close alignment.

For clutching the elements 2 and 3, any suitable speed-responsive means may be provided. An example of one means suitable for the purpose is shown in Fig. 2. The driving member 2 has Each weight also has a curved inner surface coaxial with its outer curved surface and these inner curved surfaces are adapted to be drawn inwardly by the springs l8 against a rubber bumper 23 in the shape of a torus ring, engaged in a groove in a hub 24 formed on member 2. Each weight H has a hook 25, somewhat narrower than the rest of the weight (Fig. 2), which hook is adapted to engage in a notch 23 in the 4 other weight to limit the extent to which the weights can be thrown outwardly by centrifugal force. The clutching means described is arranged to engage and drive drum 3 only after the burner fan has attained a predetermined high speed as closely as feasible to run speed.

The auxiliary fan I is arranged to control an auxiliary air inlet to the burner fan. This air inlet may be provided by a sleeve 21 (Figs. 4 and 5) which is adapted to extend through a central hole made in the air shutter of the burner and which is adapted to be secured to the shutter by suitable screws or bolts, passing through holes 28 provided in an outturned flange 29 on the sleeve.- In some cases, it may be more convenient to provide the sleeve as part ofa new shutter, such as is shown at 30 in Figs. 6 and 7. This shutter has a central hole 3| of the proper size to receive the auxiliary fan and the sleeve is formed by a short marginal flange 32 embordering hole 3|.

The conversion unit is shown applied to an oil burner in Fig. 8. The fan housing of an oil burner is shown at 33, the fan at 34 with its hub 35 suitably secured to the projecting end of the shaft 31 of the electric motor 38, which isbolted to one end face of the housing 33. In the opposite end face is the main air inlet 33 to the burner fan. The outlet for air to pass to the nozzle of the burner is shown at 40. From the last named end face of housing 33 extends a bracket 4| in which the oil pump 42 is supported with its drive shaft 43 extending inwardly toward the fan. A flexible coupling ordinarily connects shaft 43 to the fan hub 35. Such coupling ordinarily passes through a small central hole in the air shutter 44. This shutter has fixed thereon a nut 45, threaded on a screw 46, which is rotatably mounted at its ends, one in pump bracket 4| and one in fan housing 33. This screw has a head 41 by which it may be turned. A spring 48 on the screw acts between the inner face of bracket 4| and a washer 49, held in place on the screw by a pin 50, to hold head 41 against the outer face of bracket 4|. Rotation of the shutter is prevented by a stud 5|, fixed at one end in bracket 4| and having its other end loosely engaged in an opening in the shutter. By turning screw 46, theshutter 44 may be moved toward or away from the air inlet opening 39.

In applying the conversion unit, the pump 42 is removed and also the flexible coupling by which its drive shaft 43 is connected to the hub 35 of fan 34. The air shutter 44 is removed by first removing pin 50, then turning the screw 46 until it is disengaged from nut 45, then pulling the screw axially outward until its inner end is disengaged from its bearing and pulled outwardly beyond nut 45. The stud 5| is also moved axially outward to free it from the shutter. The shutter is then lifted out. The conversion unit is now applied by sliding the splined socket I over the correspondingly splined hub 35 of the burner fan and then turning the set screw Hi to hold the hub and socket against axial displacement. The shutter 44, which was =removed, may have its small central hole enlarged to receive the auxiliary air inlet sleeve 21, which can be secured thereto by bolts 52 passed through the holes 28 in flange 23 and through suitable holes drilled in the shutter. Alternatively, a new air shutter, such as is shown at 3|! in Figs. 6 and 7, may be substituted for the old shutter. The shutter 44 or 30, as the case may be, is then put in place by sliding it over the clutchdrum 3 and fan i; then l "m replacing the screw 4! by threading it overthe on was memoir in motion at the 4!. inserting its inner unthreaded end'in its bearing in the fan housing II; and finally applyin is also put back in place (it may be held to the bracket I by a set screw I3). The oil pump 42 is next put in place in the bracket ll and its driving shaft 43 is inserted in the bore in the hubs of the driven clutch drum 3. .The set screw Having completed the installation of the con- .version unit, the usual sheet metal-enclosures ll for the shutter and pump are applied as'indicated.

It next becomes necessary to adjust the air shutter 44 to get the proper rate of flow of air to the burner. This is done by turning the screw 46 to move the shutter toward or awa from air inlet 39 to vary the effective area of the inlet. It will be of advantage now to move the shutter closer to the inlet than it was before in the use of the prior art structure which is herein described as converted, because the invention involving the changed shutter, provides for the admission of additional airduring the starting and stopping intervals of operation of the burner and enables the rate of air supply during normal running intervals of operation of the burner to be adjusted closely to the .rate theoretically necessary for perfect combustion. The adjustment of the air shutter is made while the burner is in operation with the auxiliary fan I revolving in the central opening of the air shutter. This fan I. when revolving tends to draw air out of the may be set so that a very'high percentage of C02,

results to give excellent combustion and high efliciency in the burning of the oil. This may be safely done because the difficulties due to smoky operation during the starting and stopping intervals are overcome by the use of the conversion unit of this invention as will-be explained below.

In operation, when the burner motor 38 is started, the fan 34 is set in operation but the oil pump 42 and the auxiliary fan I do not immediately revolve. With the auxiliary fan stationary, the burner fan will draw in air not only through its usual inlet but also through the additional inlets comprising the spaces between the blades of fan I and the annular space representing the clearance between the tips of the blades of fan I and the inner periphery of air sleeve 21 which isa casing for auxiliary 'fan I. In other words,

the area of the inlet to the main fan has been increased by the area of the spaces just mentioned. The burner fan attains high speed before the oil pump and auxiliary .fan start to be driven. The burner 'fan thus has ahead start pin I to hold spring '48 inplace' and cause itto i draw head 41 against bracket II. The stud II nossle at. sufllclent velocity for good mixing and at arate'whi'ch is'substantially greater than is used during normal runningintervals of operation oi the burner. Consequently when oil is emitted from the nozzle. i re is an excess air 'supply to produce a lean? mixture and combus tion occurs without the put! of smoke usually incident to starting up of the burner. Once the fan :4 has acquired sufficient speed to produce the desired air flow at the nozzle, the pump will space on the inlet side of the burner fan. This be operated to force 011 to the nozzle and the auxiliary fan I will be operated toreduce the rate of airflow through the auxiliary air inlet so that the rate of" air supply to the burner is reduced to that necessary to produce efllcient combustion in the burning of-the oil. The conditions thatnow exist are the same as they were, when the adjustment of the air shutters was made, and the air-oil ratio is that necessary to give a high percentage of CO2 and thus efliclent combustion in the burning of the oil. When the burner is stopped, the oil pump and auxiliary fan I quickly come to rest. As soon as the speed of the motor slackens' a little following the opening of its supply circuit, the speed-responsive clutch opens and this is followed by a sudden stopping of the oil pump and fan I because of the load on the oil pump. The motor 38 and fan 3|, however, continue to turn for several seconds due to the momentum of the heavy rotor of the motor and the comparatively light-load on the fan of the character shown and the auxiliary air inlet is rendered more eifective by the stopping of fan I. Hence, air flow at substantial velocity and at a rate large enough to maintain a lean mixture is maintained after the pump stops and the main fan coasts under the-momentum as stated. Thus, the pull or smoke that usually occurs during the stopping interval of operation of the ordinary bumer is eliminated and the burner stops quietly and without any smoke to cause objec- I tionable soot deposits in the heating apparatus. The use of a sleev such as 21, or a flange, such as 32, on the air shutter has the advantage that it enables considerable latitude in the relative axial positions of the fan I and shutter. For example, the shutter might be located in a plane, transverse to the axis of the fan I and to the left of a similar plane passing through the left hand ends of the blades of fan I, provided there is a sleeve to extend to the right sumciently to cover a part of fan- I. And the shutter can be adjusted over a wider range when a sleeve is used. Except for these reasons, the sleeve or flange can be reduced to a very short length.

The invention provides a unit which may be applied to various oil burners of the gun type to eliminate smoky operation during the starting and stopping intervals and to enable the burner to operate with greater efliciency during normal running intervals or operation of the burner.

This invention has a relation to that of my copending application Serial No. 672,106, filed May 24, 1946, in the following way. In said application an improved oil burner is disclosed such as would be supplied by an oil burner manufacturer in trade competition with burners not having the structure, mode of operation and results as disclosed in the invention of said application. The burner referred to in this application as one before and after it has been converted. by the structure claimed herein, is considered as a prior art burner which has been sold and but in use by the buyer before conversion, which he wants :apoaace structure disclosed and claimed in this application.

The useful economic results of the present invention are the manufacture of the structure -claimed herein, its distribution to oil burner dealers, and the use by them for converting any suitable type of oil burner already installed in a house to the substantially improved form. Ordinarily the burner improvements of said copending application would be available to the public only in the new model burners tending to cause many old model burners to be taken out and new ones put in. The purpose of the present invention is to provide new and useful structure resulting in the public being able to convert their old model burners to operate more efficiently in the burning of oil for house heating use. It is not ordinarily feasible to have such burners taken out of use, sent to a factory and rebuilt to get new model advantage. The feasible way to get the conversion from old to new model burners, i. e. new enough to get most of the sub- SI-C'Mtial results of the new improvements is to supply local dealers with the useful structure to be used as pointed out and claimed herein. It should be kept in mind that under the circumstances of the oil burner business, local mechanics, the ones busy in servicing the burners in Y the user's homes, will install the structure of this invention and it is adapted for their benefit in selling along with their service and for the benefit of users who can vnow have their old burners put into condition to closely approximate the performance of new model improved burners all without going to the expense of discarding the old burner and buying an entirely new model.

Having disclosed my invention, I claim:

1. A conversion unit for substitution for the driving coupling between the motor-driven airsupply fan and oil-supply pump of an oil burner.

comprising. ;an auxiliary fan, speed-responsive driving means therefor consisting of a driving member, a driven member inthe form of a-drum. a spring-retracted weight carried by the driving member and movable outwardly by centrifugal force to engage the inner periphery of said drum and drive the latter after the driving member has attained a predetermined speed, and coupling means on the driving and driven members for driving and driven connections, said auxiliary fanlconsisting of fan blades formed on and pro- -jecting outwardly from the outer peripheral portion of said drum.

2. A conversion unit for substitution for the driving coupling between the motor-driven airsupply fan and oil-supply pump of an oil burner, comprising, an auxiliary fan, speed-responsive driving means therefor consisting of a driving. member, a driven member in the form of a drum, a spring-retracted weight carried by the driving member and movable outwardly by centrifugal force to engage the inner'periphery of said drum and drive the latter after the driving member has attained a predetermined speed, and coupling means on the driving and driven members for driving and driven connections, said auxiliaryfan consisting of fan blades formed on and projecting outwardly from the outer peripheral portion of said drum, and a housing for said fan consisting of a sleeve adapted to be stationarily supported and within which the fan is revoluble.

JOSEPH ,A. 1.00m, REFERENCES orrEn 'UNITEDSTA'IES PATENTS Name Date Logan Jan. 1, 1935 Number 

